This invention relates to processes for the recovery of poly(arylene sulfide) from a poly(arylene sulfide) reaction mixture. In one of its aspects, the invention relates to the separation of solid and liquid components of the reaction mixture of the reaction of polyhalo-substituted aromatic compounds and polar organic solvent to provide poly(arylene sulfide). In another of its aspects, this invention relates to the recovery of particulate poly(arylene sulfide) by separation from the other components of this reaction mixture. In still another aspect of the invention, it relates to vacuum evaporation processes.
In one concept of this invention it provides a method for separating the reaction mixture of the reaction of polyhalo-substituted aromatic compounds and polar organic solvent into a particulate poly(arylene sulfide) that is recovered from the reaction mixture and other components that can be separated for recovery or disposal.
A basic process for the production of arylene sulfide polymers from polyhalo-substituted cyclic compounds containing unsaturation between adjacent ring atoms, wherein the halogen atoms attached to ring carbon atoms react with an alkali metal sulfide in a polar organic compound at an elevated temperature is disclosed in U.S. Pat. No. 3,354,129. Since the disclosure of that invention a great amount of experimental work has been completed which resulted in the disclosure of methods for both batch and continuous operations to produce poly(arylene sulfides) not only from p-dihalobenzenes but also containing polyhalo aromatic compounds having more than two halogen substituents per molecule and with the addition of various polymerization modifying compounds such as alkali metal carboxylates. Processes have also been disclosed in which various reactants can be premixed to form reaction complexes before all of the reactants are brought together at polymerization conditions. All of these processes have in common the production at a temperature above that at which poly(arylene sulfide) is in molten phase, of a reaction mixture containing poly(arylene sulfide) and a polar organic solvent along with various impurities and unreacted reactants from which solid poly(arylene sulfide) is recovered. The process of the present invention is also adaptable for recovery of granular poly(arylene sulfide) from any slurry which contains granular poly(arylene sulfide) with polar organic solvent, alkali metal halide, poly(arylene sulfide) oligomers, unreacted reactants from the polymerization process and water.
It is therefore an object of this invention to provide a method for recovering the granular poly(arylene sulfide) particles from a slurry comprising granular poly(arylene sulfide), polar organic solvent, alkali metal halide, particularly sodium chloride, poly(arylene sulfide) oligomers, unreacted reactants and water. Another object of this invention is to provide a method for recovering relatively large, granular poly(arylene sulfide) particles from a reaction mixture containing poly(arylene sulfide) and polar organic solvent. It is another object of this invention to provide a method for recovering poly(arylene sulfide) having a particle size distribution resulting in improved filterability and reduced dustiness as compared to the resin recovered by solvent flashing methods. It is still another object of the invention to provide a method for recovering poly(arylene sulfide) having a particle size distribution that will eliminate the need for special treatments or handling of the recovered particles prior to their subsequent uses. It is still another object of the invention to produce poly(arylene sulfide) having a generally higher bulk density than is produced by solvent flashing methods of recovering the polymer from its reaction mixture. It is still another object of this invention to provide a method for recovery of poly(arylene sulfide) which facilitates separation of arylene sulfide oligomers from the reaction mixture. It is another object of this invention to produce useful manufactured articles from poly(arylene sulfide) recovered by the method of this invention. It is still another object of this invention to provide a method for recovery of poly(arylene sulfide) which results in particulate polymer suitable for further treatment and the production of manufactured articles such as films, sheets, fibers, molded articles, and extruded articles.
Other aspects, concepts, and objects of this invention will become apparent to those reading this disclosure and studying the appended drawings and claims.